Pinch valve

ABSTRACT

A pinch valve is provided with a main body ( 10 ) accommodating a tube body ( 11 ), a cylinder body ( 2 ) having an upper cylinder portion ( 17 ) and a lower handle support portion ( 3 ), a piston accommodated in the cylinder portion, a pressing piece ( 9 ) fixed to the piston for pressing the tube body, a cylindrical handle ( 1 ), a hollow stem ( 4 ), and a piston pusher ( 5, 6 ). The handle has a female screw portion, and a male screw portion having a pitch larger than the pitch of the female screw portion and adapted to be screwed with the female screw portion formed on the handle support portion. The stem has a male screw portion adapted to be screwed with the female screw portion of the handle on outer periphery, and is accommodated in the cylinder body. The piston pusher is inserted into the stem so that the bottom end surface thereof comes into contact with the top end of the piston and is urged toward the piston by a spring.

TECHNICAL FIELD

The present invention relates to a pinch valve used in a fluid transportpipeline in various industrial fields, such as chemical factories,semiconductor production, food processing, biotechnology or the like,and more particularly, to a pinch valve which has an opening degreeadjustment mechanism enabling the opening degree to be adjusted moreprecisely and easily.

BACKGROUND ART

The applicant invented a pinch valve, improved over the conventionalpinch valve, which is extremely compact, enhances the durability of atube body laid inside during valve opening/closing operations, andenables fine adjustment of the flow rate and filed an application for itpreviously (Japanese Patent Application No. 2001-179027). Explainingthis structure with reference to FIG. 8, it is provided with a cylinderbody 52 having a cylinder portion 61 having a female screw portion 60for adjustment of the opening degree at the top inner periphery thereofand an air port 62 communicating with the bottom end of the cylinderportion 61, a cylindrical handle 54 having at a bottom outer peripherythereof a male screw portion 63 adapted to be screwed with the femalescrew portion 60 of the cylinder body 52 for adjustment of the openingdegree, a disk-shaped spring carrier 55 sandwiching the spring 53 withthe top end surface of the recess 64 of the handle 54, a connecting bar56 engaged with the top of the handle 54 and having a bottom end surfaceconnected with the spring carrier 55 so that the spring 53 is sandwichedbetween the handle 54 and the spring carrier 55, a piston 57 sliding upand down against the inner pheriphery of the cylinder portion 61 in asealing manner and having a connecting portion 66 suspended from thecenter of the piston 57 so as to extend in a sealing manner through athrough hole 65 formed in the center of the bottom surface of thecylinder body 52, a pressing piece 58 fixed to the bottom end of theconnecting portion 66 of the piston 57, and a tube body 59 comprised ofan elastic member held inside the body 51 and pressed against thepressing piece 58.

The operation of this pinch valve will be described below. When thehandle 54 is turned in the opening direction in a fully closed statewherein the valve is fully closed as shown in FIG. 8, the bottom endsurface of the spring carrier 55 is raised via the connecting bar 56.Along with this, the fluid pressure of the fluid flowing through theinside of the tube body 59 and the elastic force of the tube body 59cause the pressing piece 58 to be pushed up. As a result, the piston 57rises and the tube body 59 becomes the intermediate opening degree. Onthe other hand, when compressed air is supplied from the air port 62 tothe first space portion 67 in a state wherein the valve is adjusted tothe intermediate opening degree, the pressure of the compressed aircauses the piston 57 to start to rise while sliding at its peripheryagainst the inner periphery of the cylinder portion 61. Along with this,the top end of the piston 57 rises while compressing the spring 53 viathe spring carrier 55 and the pressing piece 58 rises via the connectingportion 66 suspended from the piston 57. Finally, the top end surface ofthe pressing piece 58 reaches the top end surface of the oval slitformed at the bottom end surface of the cylinder body 52, whereupon therise of the piston 57 and the pressing piece 58 stops and the pinchvalve becomes the fully opened state.

Further, when the supply of air from the air port 62 to the first spaceportion 67 is stopped and the valve is opened to the atmosphere in thefully opened state, the piston 57 starts to descend due to theresiliency of the spring via the spring carrier 55 abutting against thespring 53 Along with this, the pressing piece 58 also descends via theconnecting portion 66 suspended from the piston 57. Finally, the bottomsurface of a flange 68 of the connecting bar 56 reaches the bottomsurface of the recess 64 formed at the top of the handle 54, whereuponthe descent of the piston 57 and the pressing piece 58 is stopped andthe pinch valve is adjusted to an intermediate opening degree. Byadjusting the opening degree of the handle 54 in this way, it becomespossible to finely adjust the flow rate.

However, in a pinch valve of the above configuration, the adjustment ofthe stroke of the pressing piece for adjusting the opening degree of thetube body is proportional to the amount of turning of the handle 54 andthe proportional constant of the same is determined by the pitch of themale screw portion of the handle. Therefore, to adjust the stroke moreprecisely, adjustment by an extremely small angle of rotation isnecessary. This results in the large operation error and therefore makesfine adjustment difficult. To enable finer adjustment, it is sufficientto make the pitch of the male screw portion of the handle 1 smaller, butmaking the pitch smaller causes problems in strength and in processingprecision and therefore is limited.

DISCLOSURE OF INVENTION

The present invention has been made in consideration with the aboveproblems of the prior art, and an object thereof is to provide a pinchvalve enabling fine adjustment of the opening degree, that is, fineadjustment of the flow rate, in a conventional pitch valve, moreprecisely and easily.

To achieve the above object, there is provided a pinch valve, whichincludes a main body formed with a groove for receiving an elastic tubebody forming part of a flow passage of a fluid; a cylinder body of aclosed-bottom tubular shape fixed to the main body and having a handlesupport portion provided at an inner periphery thereof with a femalescrew portion, a cylinder portion arranged below the handle supportportion and formed with a through hole in a center of a bottom thereof,and an air port communicating with a bottom end of the cylinder portionat a peripheral side thereof; a piston sliding up and down against aninner periphery of the cylinder portion in a sealing manner and having aconnecting portion suspended from a center thereof so as to extendthrough the through hole of the cylinder portion in a sealing manner; apressing piece fixed to a bottom end of the connecting portion of thepiston so as to press against the tube body when the piston descends; acylindrical handle having a female screw portion formed on an innerperiphery thereof and a male screw portion formed on a bottom outerperiphery thereof and having a pitch larger than a pitch of the femalescrew portion, the male screw portion of the cylindrical handle adaptedto be screwed with the female screw portion of the handle supportportion; a hollow stem having an annular projection formed at a topinner periphery thereof and a male screw portion formed on an outerperiphery thereof so as to be screwed with the female screw portion ofthe handle, and accommodated in the cylinder body so as to allow thehollow stem to slide up and down and so as to prevent the hollow stemfrom turning; and a piston pusher having an upper flange formed at a topend thereof and a lower flange formed at a bottom end thereof, thepiston pusher inserted in the hollow stem so as to be able to slide upand down with a bottom end surface thereof contacting a top end of thepiston, the upper flange engaging with a top surface of the annularprojection of the hollow stem so that a spring is supported between thelower flange and a bottom surface of the annular projection of thehollow stem.

The feature of the present invention lies in the point of forming screwportions on the inner periphery and the bottom of the outer periphery ofa single cylinder handle and increasing the pitch of the male screwportion formed on the bottom of the outer periphery of the handle fromthe pitch of the female screw portion formed on the inner periphery ofthe handle. Due to this, when the handle is turned by one turn, thehandle rises or descends by exactly the pitch of the male screw portionwith respect to the handle support portion screwed with the male screwportion formed on the outer periphery of the handle and the cylinderbody connected to the same, while the hollow stem screwed with thefemale screw portion of the inner periphery of the handle moves in thereverse direction from the handle by exactly the pitch of the femalescrew portion with respect to the handle. That is, the hollow stem movesrelative to the handle support portion and the cylinder body by exactlythe pitch difference between the female screw portion and the male screwportion of the handle due to one turn of the handle, so that theposition of the hollow stem can be changed by exactly a fine amount. Onthe other hand, due to the interaction between the annular projection ofthe hollow stem, the spring, and the two flanges of the piston pusher,the vertical position of the hollow stem defines the vertical positionof the piston pusher and defines the opening degree of the tube body bythe pressing piece via the piston. Therefore, according to the structureof the pinch valve of the present invention, fine adjustment of theposition of the hollow stem in the vertical direction can be achieved,so that fine adjustment of the opening degree of the tube body (that is,the valve opening degree) can be achieved by the pressing piece via thepiston.

Further, since the piston pusher is inserted into the hollow stem so asto be able to slide up and down with a spring placed between the lowerflange of the piston pusher and the annular projection of the hollowstem, a supply of air to the cylinder portion through the air portallows the piston pusher to rise with respect to the hollow stem againstthe force of the spring regardless of the vertical position of thehollow stem with respect to the cylinder body. Accordingly, the pinchvalve can be changed by supplying or releasing air to or from thecylinder portion between the intermediate opening degree state and thefully opened state, without any accompanying change of the position ofthe hollow stem due to turning of the handle.

Preferably, a pitch difference between the female screw portion and themale screw portion of the handle may be set in a range of from 1/20 to ⅕of the pitch of the male screw portion. If the pitch difference issmaller than 1/20 of the pitch of the male screw portion, the stroke ofthe handle becomes too large and the valve height becomes larger.Further, if the pitch difference is larger than ⅕ of the pitch of themale screw portion, fine adjustment of the valve opening degree becomesno longer possible. By selecting the pitch difference between the malescrew portion and the female screw portion in the above range, it ispossible to adjust the stroke of the handle as desired, so fineadjustment of a broad range of opening degree becomes possible.

Alternatively, preferably, an inner periphery of a portion between thehandle support portion and the cylinder portion of the cylinder body isformed with a recess, and the hollow stem has a flange accommodated inthe recess of the cylinder body at a bottom end thereof. Accommodatingthe flange of the hollow stem in the recess of the cylinder body allowsthe hollow stem to be moved up and down by turning the handle, whilepreventing it to turn with respect to the cylinder body.

Alternatively, preferably, the pressing piece is accommodated in an ovalslit extending in a direction perpendicular to an axis of the flowpassage at a bottom end of the cylinder body. By accommodating thepressing piece in the oval slit, rotation of the pressing piece isinhibited.

Alternatively, preferably, connecting portions for connecting the tubebody to another tube are provided at the two sides of the main body.These connecting portions make it easy to connect the pinch valve to anoutside flow passage.

The material of the tube body of the pinch valve according to thepresent invention may be EPDM, a fluororubber, silicone rubber, afluororesin, or a composite of a fluororubber and silicone rubber etc.,but is not particularly limited. However, a composite of a fluororesinand silicone rubber may he mentioned as a particularly preferablematerial.

The material of the handle, cylinder body, handle support portion,hollow stem, and body may be a metal, plastic, or other rigid material,but is not particularly limited. PVC, PVDF, or another fluororesinplastic may be mentioned as a particularly preferable material.

Further, the material of the connecting portion forming the connectingbody is not particularly limited so long as it is a plastic or othermaterial having chemical resistance. PTFE, PVDF, PEA, or anotherfluororesin plastic may be mentioned as a particularly preferablematerial.

BRIEF DESCRIPTION OF DRAWINGS

These above and other objects, features and advantages of the presentinvention will be described in more detail below based on the preferredembodiments of the present invention with reference to the accompanyingdrawings, wherein:

FIG. 1 is a vertical cross-sectional view of a pinch valve in a closedstate according to an embodiment of the present invention;

FIG. 2 is a vertical cross-sectional view of the pinch valve of FIG. 1as seen from the side (in a flow passage direction);

FIG. 3 is an exploded perspective view of a handle, hollow stem,stopper, spring carrier, and spring;

FIG. 4 is a vertical cross-sectional view of the pinch valve of FIG. 1in an opened state;

FIG. 5 is a vertical cross-sectional view of the pinch valve of FIG. 4as seen from the side (in a flow passage direction);

FIG. 6 is a bottom view of a cylinder body shown in FIG. 1;

FIG. 7 is a vertical cross-sectional view of the pinch valve of FIG. 1in an intermediate opening degree state; and

FIG. 8 is a vertical cross-sectional view of the prior art.

BEST MODE FOR CARRYING OUT THE INVENTION

Although several embodiments of the present invention will be describedbelow with reference to the accompanying drawings, but the presentinvention is of course not limited to these embodiments.

A pinch valve made of PVDF according to the present invention will bedescribed with reference to the accompanying drawings.

Reference numeral 1 designates a cylindrical handle, which is providedwith a female screw portion 13 formed at the inner periphery thereof andprovided with a male screw portion 14 formed at the bottom outerperiphery thereof by a pitch larger than the pitch of the female screwportion 13 and reduced in diameter from the top end of the handle (seeFIGS. 1 and 3).

Reference numeral 2 designates a closed-bottom tube shaped cylinderbody, which is provided with a recess 15 formed at the top innerperiphery thereof and a cylinder portion 17 formed below the recess 15.The cylinder portion 17 is reduced in diameter from the recess 15 andhas a through hole 16 formed at the center of the bottom thereof.

Further, the bottom side surface of the cylinder body 2 is provided withan air port 18 communicating with the lower part of the cylinder portion17, wile the center of the bottom end surface is provided with an ovalslit 28 centered about the through hole (see FIG. 6).

Reference numeral 3 designates a support for the handle 1, which has afemale screw portion 19 formed at the inner periphery thereof andscrewed with the male screw portion 14 of the handle 1 and is fixedlyjoined at the bottom end thereof to the top end of the recess 15 of thecylinder body 2 to form part of the cylinder body 2.

Reference numeral 4 designates a hollow stem, which has a male screwportion 20 formed at the outer periphery thereof and screwed into thefemale screw portion 13 of the handle 1, an annular protection formed atthe top inner periphery thereof, and a flange 22 formed at the sidesurface of the bottom end and adapted to be accommodated in the recess15 of the cylinder body 2. Although not shown, the hollow stem 4 ishoused in the recess 15 of the cylinder body 2, so that it can move upand down due to turning of the handle 1 while it cannot be turned withrespect to the cylinder body 2 (see FIGS. 1 and 3).

Reference numeral 5 designates a cylindrical stopper, which is supportedat the inner periphery of the annular projection 21 of the hollow stem 4and is provided at the top end thereof with a flange 25 adapted to beengaged with the top surface of the annular projection 21, that is, incontact with or separated from it (see FIGS. 1 and 3).

Reference numeral 6 designates a cylindrical spring carrier, which isconnected to the bottom end of the stopper 5 and is provided at the sidesurface of the bottom end with a flange 26 engaged with the top surfaceof the piston 3 (see FIGS. 1 and 3).

In this embodiment, the stopper 5 and the spring carrier 6 are connectedand fixed by a bolt inserted through the two and a nut. However, thefixing method is not limited to this, and the two may be fixed byscrewing, welding, etc. as well. The stopper 5 and the spring carrier 6are connected and fixed in this way to form a single piston pusher.

Reference numeral 7 designates a spring, which is held sandwichedbetween the top surface of the flange 26 of the spring carrier 6 and thebottom surface of the annular projection 21 of the hollow stem 4 incontact with them. In this embodiment, one spring 7 is attached, but twoor more springs 7 may also be attached in accordance with the requiredurging force.

The piston 8 is of a disk shape, and has an O-ring attached to its outerperiphery. Further, the piston 8 has its top end surface in constantcontact with the bottom end surface of the spring carrier 6, and isaccommodated in the cylinder portion 17 of the cylinder body 2 so as tobe able to slide up any down in a sealing manner. The piston 8 isprovided at the center bottom thereof with a tubular connecting portion27 suspended from the same. The connecting portion 27 extends in asealing manner through a through hole 16 formed in the bottom center ofthe cylinder body 2. The front end of the connecting portion 27 has apressing piece 9 fixed thereto. In this embodiment, the pressing piece 9is fixed by screwing to the front end of the fastening bolt Insertedthrough the connecting portion 27.

The pressing piece 9 is formed into a rod shape overall with the partpressing against the tube body 11 being semicylindrical incross-section. It is fixed to the connecting portion 27 of the piston 8so as to perpendicularly intersect the axis of the flow passage and cutacross the tube body 11. When the valve is fully opened, it isaccommodated in an oval slit 28 which is formed at the bottom endsurface of the cylinder body 2 so as to perpendicularly intersect theaxis of the flow passage (see FIGS. 4 and 5).

Reference numeral 10 designates a main body connected and fixed to thebottom end surface of the cylindrical body 2 by a nut, bolt, etc. (notshown). The main body 10 is formed with a groove 29 of a rectangularcross-section for accommodating the tube body 11 therein which extendsalong the axis of the flow passage.

The tube body 11 is comprised of a composite of PTFE and silicone rubberobtained by stacking several layers of sheets of PTFE impregnated withsilicone rubber, and forms the flow passage in the main body 10. In thisembodiment, the material of the tube body is a composite of PTFE andsilicone rubber. However, it may also be EPDM, silicone rubber, afluororubber, composites of the same, etc. and is not particularlylimited.

Reference numeral 12 designates connecting portions made of PTFE, whichare formed by connecting body carriers 30 engaging with the grooveportion 29 of the main body 10 and the bottom of the cylinder body 2 andfixed to the cylinder body 2 and the main body 10 at the two sidesurfaces thereof, connecting bodies 32 engaging with the connecting bodycarriers 30 and connected with the tube body 11, and cap nuts 31 screwedwith the outer peripheries of the connecting body carriers 30 forfastening the connecting bodies 32 to the connecting body carriers 30.The structure of the connecting portion 12 is not limited to the presentembodiment and may be of any type so long as it is a structure forconnecting the tube of the pipeline and the tube body 11.

The operation of the pinch valve of the present embodiment having theabove configuration is as follows.

In the state where the pinch valve shown in FIG. 1 and FIG. 2 is fullyclosed, when compressed air is supplied under pressure into the cylinderportion 17 of the cylinder body 2 from the air port 18, the pressure ofthe compressed air causes the piston 8 to start to rise while sliding atits outer periphery against the inner periphery of the cylinder 17.Along with this, the top end surface of the piston 8 rises whilecompressing the spring 7 via the spring carrier 6, and the pressingpiece 9 rises via the connecting portion 27 suspended from the piston 8.Finally, the top end of the pressing piece 9 reaches the top end surfaceof the oval slit 28 formed at the bottom end of the cylinder body 2,whereupon the rise of the piston 8 and the pressing piece 9 is stoppedand the tube body 11 becomes the fully opened state (the state shown inFIGS. 4 and 5).

Next, in the state where the pinch valve shown in FIGS. 4 and 5 is fullyopened, when the supply of compressed air from the air port 18 to thecylinder portion 17 of the cylinder body 2 is stopped and the air in thecylinder portion 17 is released to the atmosphere, the piston 8 startsto descend due to the resiliency or the spring 7 via the spring carrier6 abutting against the spring 7 and along with this the pressing piece 9also descends via the connecting portion 27 suspended from the piston 8.Finally, the bottom end surface of the piston 8 reaches the bottomsurface of the cylinder portion 17, whereupon the descent of the piston8 and the pressing piece 9 is stopped and the tube body 11 becomes thefully closed state (the state shown in FIGS. 1 and 2). At this time, toprevent the pressing piece 9 from turning, the top end surface of thepressing piece 9 is positioned inside the oval slit 28 of the cylinderbody 2.

Next, the method of adjusting the pinch valve of the present embodimentto an intermediate opening degree will be described.

In the state shown in FIG. 1, that is, the state where the pinch valveis fully closed, when the handle 1 is turned by exactly one turn in theopening direction, the handle 1 rises by exactly the pitch of the malescrew portion 14 formed on the outer periphery of the handle 1.Conversely, the hollow stem 4 screwed into the female screw portion 13formed on the inner periphery of the handle 1 and having a pitch smallerthan that of the male screw portion 14 of the handle 1 descends byexactly the pitch of the female screw portion 13 of the handle 1.Overall, the hollow stem 4 rises by exactly the difference in pitchbetween the two. For example, when the pitch of the male screw portion13 formed on the inner periphery of the handle 1 and the female screwportion 20 of the hollow stem 4 are made 1.8 mm and the pitch of themale screw portion 14 formed on the outer periphery of the handle 1 andthe female screw portion 19 formed on the inner periphery of the handlesupport portion 3 are made 2.0 mm, the hollow stem 4 rises 0.2 mm byturning the handle one turn. That is, it rises by exactly 1/10 of thescrew portion pitch of the male screw portion 14 formed on the outerperiphery of the handle 1. Along with this, the bottom end surface ofthe spring carrier 6 is raised via the stopper 5 and the pressing piece9 is pushed up by fluid pressure of the fluid flowing through the insideof the tube body 11 and the elastic force of the tube body 11. As aresult, the piston 8 rises and the tube body 11 is adjusted to anintermediate opening degree (the state shown in FIG. 7).

On the other hand, the transition from the state wherein the pinch valveis adjusted to the intermediate opening degree to the fully opened stateor from the fully opened state to the intermediate opening degree statemay be performed by supplying air from the air port 18 or releasing thepressurized air in the same manner as described above.

As described above, the pinch valve of the present embodiment can notonly start and stop the flow of fluid, but also allow fluid to passthrough it at an intermediate opening degree. Therefore, it is possibleto use this as a back pressure valve in a closed loop pipeline of asystem such as a semiconductor production system.

Since the pinch valve of the present invention has the above structure,using this enables the opening degree to be adjusted -more precisely andeasily compared with conventional valves and enables the fine adjustmentof the flow rate to be performed quickly over a broad range.

While the present invention has been described with reference tospecific embodiments shown in the accompanying drawings, theseembodiments are for explanatory purposes and are not limitative in anysense. Therefore, the scope of the present invention is only limited bythe claims. The preferred embodiments of the present invention can bemodified and chanced without departing from the scope of the claims.

1. A pinch valve comprising: a main body formed with a groove forreceiving an elastic tube body forming part of a flow passage of afluid; a cylinder body of a closed-bottom tubular shape fixed to saidmain body and having a handle support portion provided on an innerperiphery thereof with a female screw portion, a cylinder portionarranged below said handle support portion and formed with a throughhole in a center of a bottom thereof, and an air port communicating witha bottom end of said cylinder portion at a peripheral side thereof; apiston sliding up and down against an inner periphery of said cylinderportion in a sealing manner and having a connecting portion suspendedfrom a center thereof so as to extend through said through hole of saidcylinder portion in a sealing manner; a pressing piece fixed to a bottomend of said connecting portion of said piston so as to press againstsaid tube body when said piston descends; a cylindrical handle having afemale screw portion formed on an inner periphery thereof and a malescrew portion formed on a bottom outer periphery thereof and having apitch larger than a pitch of said female screw portion, said male screwportion of said cylindrical handle adapted to be screwed with saidfemale screw portion of said handle support portion; a hollow stemhaving an annular projection formed at a top inner periphery thereof anda male screw portion formed on an outer periphery thereof so as to bescrewed with said female screw portion of said handle, said hollow stemaccommodated in said cylinder body so as to allow said hollow stem toslide up and down and so as to prevent said hollow stem from turning;and a piston pusher having an upper flange formed at a top end thereofand a lower flange formed at a bottom end thereof, said piston pusherinserted in said hollow stem so as to be able to slide up and down witha bottom end surface thereof contacting a top end surface of saidpiston, said upper flange engaging with a top surface of said annularprojection of said hollow stem so that a spring is supported betweensaid lower flange and a bottom surface of said annular projection ofsaid hollow stem.
 2. The pinch valve according to claim 1, wherein apitch difference between said female screw portion and said male screwportion of said handle is in a range of from 1/20 to ⅕ of the pitch ofsaid male screw portion of said handle.
 3. The pinch valve according toclaim 1, wherein an inner periphery of a portion between said handlesupport portion and said cylinder portion of said cylinder body isformed with a recess and said hollow stem has a flange accommodated insaid recess of said cylinder body at a bottom end thereof.
 4. The pinchvalve according to claim 3, wherein a pitch difference between saidfemale screw portion and said male screw portion of said handle is in arange of from 1/20 to ⅕ of the pitch of said male screen portion of saidhandle.
 5. The pinch valve according to claim 1, wherein said pressingpiece is accommodated in an oral slit extending in a directionperpendicular to an axis of said flow passage at a bottom end of saidcylinder body.
 6. The pinch valve according to claim 5, wherein a pitchdifference between said female screw portion and said male screw portionof said handle is in a range of from 1/20 to ⅕ of the pitch of said malescrew portion of said handle.
 7. The pinch valve according to claim 1,wherein connecting portions for connecting said tube body to anothertube are provided at the two sides of said main body.
 8. The pinch valveaccording to claim 7, wherein a pitch difference between said femalescrew portion and said male screw portion of said handle is in a rangeof from 1/20 to ⅕ of the pitch of said male screw portion of saidhandle.
 9. The pinch valve according to claim 1, wherein a material ofsaid tube body comprises EPDM, a fluororubber, silicon rubber, afluororesin, or a composite of them.
 10. The pinch valve according toclaim 9, wherein a pitch difference between said female screw portionand said male screw portion of said handle is in a range of from 1/20 to⅕ of the pitch of said male screw portion of said handle.
 11. The pinchvalve according to claim 9, wherein said tube body is comprised of acomposite of a fluororesin and silicone rubber.
 12. The pinch valveaccording to claim 11, wherein a pitch difference between said femalescrew portion and said male screw portion of said handle is in a rangeof from 1/20 to ⅕ of the pitch of said male screw portion of saidhandle.